<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
		<style type="text/css">
			* {
				margin: 0;
				padding: 0;
			}

			#myCan {
				background-color: skyblue;
			}
		</style>
	</head>
	<body>
		<canvas id="myCan" width="1000px" height="800px"></canvas>
		<script type="text/javascript">
			var oC = document.getElementById('myCan');
			var ctx = oC.getContext('2d')
			// for(var i=10;i<300;i+=10){
			// 	ctx.arc(i,200,i,0,2*Math.PI);
			// }
			// ctx.stroke();
			
			// ctx.fillStyle = 'indigo';
			for (var i = 10; i < 100; i += 10) {
				ctx.beginPath();
				ctx.arc(i, 200, i, 0, 2 * Math.PI);
				ctx.fill();
				ctx.stroke();
			}
		</script>
	</body>
</html>
